现今中国东北地区地球动力学环境

The Present Geodynamic Environment of Northeast China

中国东北地区地震构造以盆地群及控制盆地群的北东向断裂为主要特征,其中松辽盆地及控制该盆地的北东向断裂最具代表性,该盆地也是区域地震活动最强烈的地区。日本大地震后对中国东北地区主要活动断裂触发的库仑破裂应力中,北东向展布的大多增加,从西北至东南、从西南至东北具有逐渐增加的特点;北西向展布以及近东西向展布的大多减小,且从西至东、从西北至东南的减小值逐渐增大。日本大地震改变了中国东北地区与日本本岛的基本运动趋势,日本大地震的发生使中国东北地区由原来的挤压状态改变为拉张状态。在2002~2018年、2006~2018年2个时段的运动趋势中,日本大地震对中国东北地区的影响仍非常显著,现今中国东北地区的地球动力学环境仍将处于日本大地震的影响之中,对较为规律的中国东北地区浅源地震和深源地震的韵律性特征将产生一定影响。1999年开始的第5活动期已经结束,或将进入第6活动期前的间歇平静期,或仍将持续一段时间,还需时间的验证。

The seismic structure in northeast China is mainly characterized by the basin group and the northeast-trending faults which controlling basin group.The Songliao basin and the northeast-trending fault controlling the basin are the most representative.The basin is also the region with the strongest seismic activity in the region.Most of the Coulomb rupture stresses triggered by major active faults in northeast China after the Tohoku earthquake increased in the northeast direction,from northwest to southeast,and from southwest to northeast,with gradually increasing characteristics;the distribution in the north-west and near east-west direction is mostly decreasing,and the decreasing value from west to east and from northwest to southeast is a gradual increasing process.The Tohoku earthquake in Japan changed the basic movement trend of northeast China and the main island of Japan.The occurrence of the Tohoku earthquake in Japan changed the original squeezed state of northeast China into a stretched state.In the two trends of movement from 2002 to 2018 and from 2006 to 2018,the impact of the Tohoku earthquake on northeast China is still very significant,and the geodynamic environment in northeast China will still be under the influence of the Tohoku earthquake.It will have a certain influence on the rhythmic characteristics of shallow and deep source earthquakes in the relatively regular northeast China.The fifth activity period beginning in 1999 has ended,or entered the intermittent calm period before the sixth activity period,or it will continue for a period of time,and time verification is required.